Machine for grinding double helical gears



July 22, 1958 I u s 2,843,977

MACHINE FOR GRINDING DOUBLE HELICAL GEARS Filed Jan. 16, 1956 2Sheets-Sheet l I N VENTOR ATTORNEYS .July 22 1958 A. H. KUHNS 2,343,977

MACHINE FOR GRINDING DCUBLE HELICAL GEARS Filed Jan. 16, 1956' 2Sheets-Sheet 2 I N VE NTOR ATTORNEYS United States Patent MACHENE FORGRINDING DOUBLE HELICAL GEARS Austin H. Kuhns, Greenwich, Conn.,assignor to Farrel- Birminghaan Company, Incorporated, Anscnra, Conan, acorporation of Connecticut Application January 16, 1956, Serial No.559,303

Claims. (Cl. 51-142) This invention relates to gear-grinding machines,and more particularly to a device for grinding or finishing the teethupon a gear blank by means of a traveling abrasive belt or othertraveling flexible member, either covered with abrasive or havingabrasive or cutting or grinding members secured thereto.

Gear grinding machines which have generally been used in the past employrotary grinding Wheels, the grinding wheels rotating on their own axesand being engaged with the surface of a tooth of the gear to be ground.With machines of this character the grinding process is a relativelyslow one as the grinding wheel can only engage local areas on the toothto be ground, and it is, therefore, necessary for the machine to operatethrough a combination of a rolling action to cover the curved portion ofthe tooth together with a motion parallel to the length (width of thegear) of the tooth to cover the Whole face of the tooth.

In the gear-grinding machine of the present invention a rectilinearlytraveling belt is employed, the operativeportion of which travelsparallel to the axis of the gear so that it will grind over the entirelength of the face of the tooth and it is, therefore, only necessary toroll the gear relatively to the traveling belt to grind the entire faceof the tooth. This rolling action is readily obtained by the combinationof a reciprocating movement imparted to the supporting mechanism for thetraveling belt and a rotary or oscillating movement of the gear blank.

In the present application I have illustrated a device particularlyuseful in the grinding of helical or double helical gears although it isapplicable to the grinding of gears of other types. In the mechanismillustrated, a pair of traveling belts are employed, each of these beltsbeing adapted to move across the face of a gear tooth upon one half ofthe gear, the two belts being adapted to approach each other closely inthe gap between the teeth at the center of the gear and to traveloutwardly through this gap out of engagement with the gear teeth.

Moreover, provision is made for adjusting the angle of the operative runof the belt so that it may be adapted to helical gears, the teeth ofwhich have various helix angles and, if desired, one of the belts may beemployed in finishing the teeth of spur gears.

As illustrated, the belts are mounted upon three pulleys so that thebelt travels around a triangular course, one of these pulleys beingemployed to drive the belt and a second being a pulley of small sizewhich may be disposed within the gap between the teeth of a doublehelical gear. Also a backing member is provided for the operative oreffective grinding area of the belt so that the latter will be heldfirmly against the face of a tooth and engage the entire length(widthwise of the gear) of a tooth at one time.

One object of the present invention is to provide a new and improvedgear-grinding mechanism which will effect a saving of time in theoperation of finishing gears.

A still further object of the invention is to provide a ice geargrinding mechanism of simple construction which will operate eflicientlyin the grinding of double helical or spur gears.

Still another object of the invention is the provision of agear-grinding machine in which the gear-grinding mechanism is actuatedalong the face of the gear tooth in a rectilinear path substantiallyparallel to the axis of the gear blank and in which the gear blank andgrinding belt are moved in timed relation in order that the belt coverthe entire surface of the teeth of the gear.

Still another object of the invention is to provide a gear-grindingmachine as previously described wherein the gear may be indexed withrespect to the grinding belt after the grinding of one tooth has beenfinished in order to enable the belt to engage and grind a furthertooth.

A further object of the invention is to provide a novel machine forgrinding gears, and particularly gears of double helical form.

To these and other ends the invention consists in the novel features andcombinations of parts to be hereinafter described and claimed.

In the accompanying drawings:

Fig. 1 is a front elevational view of a gear-grinding machine embodyingmy invention, some parts being broken away;

Fig. 2 is a top plan view of the machine;

Fig. 3 is a sectional view on line 33 of Fig. 2 wi some parts beingbroken away;

Fig. 4 is a sectional view on line 4--4 of Fig. 3; and

Fig. 5 is a fragmentary top plan view showing the grinding of a spurgear by my improved mechanism.

To illustrate a preferred embodiment of my invention I have shown in thedrawings a gear grinding mechanism comprising base or frame portions 10and 11, the portion 10, as will be hereinafter described, serving as asupport for the grinding mechanism, and the portion 11 serving as asupport for the gear blank. A hollow shaft 12 is rotatably mounted bysuitable bearings within the supporting base portion 11, this shaftcarrying at its upper end a table or support 13 upon which the gearblank 14 is adapted to be secured, as shown in dotted lines in Figs. 1and 3.

Secured at the lower end of the shaft 12 is a bevel gear 15 which mesheswith a bevel gear 16 carried by a sleeve 17. This sleeve is rotatablymounted in the support 11 by suitable bearings 18, and secured to theprojecting end of this sleeve is an indexing wheel 19.

The base 10 is provided with parallel ways 21 upon which is mounted areciprocating carriage 22. The reciprocation of the carriage may beeffected hydraulically by means of a cylinder 23 carried by thesupporting base and a piston rod 24 secured at 25 to the end of thecarriage. It will, of course, be understood that suitable connections(not shown) are provided for introducing fluid pressure into thecylinder to effect reciprocation of the carriage over a path of thelength desired depending on the dimensions of the tooth to be ground.The carriage may, of course, be reciprocated by means other than thatshown without departing from the present invention.

As shown more particularly in Fig. 3, a shaft 26 is rotatably mounted atone end in bearings 27 carried by a standard 28 which may be a part ofthe base 1%, and the other end of this shaft is freely mounted withinthe sleeve 17 previously described. This shaft projects outwardly fromthe sleeve 17 and upon its outer end is secured a disk 36) havingrecesses 31 in its periphery to cooperate with the indexing wheel 19previously described.

A pin 32 is removably mounted in the flange 33 of the indexing wheel,and the inner end of this pin is received in one of the recesses 31 soas to connect the 3 disk 30 with the indexing wheel 19. It will beunderstood that when it is desired to index the work table 13 so as topresent a subsequent tooth to the grinding mechanism, the pin 32 may bewithdrawn from one of the recesses 31 and the indexing wheel rotatedwith respect to the disk 30 and again connected thereto by the pin 32.

It will be understood that the particular indexing means shown in purelyillustrative, and other suitable indexing means, either manual orautomatic, may be provided, if desired. With this arrangement it will beapparent that the work table 13 will be actuated by the shaft 26 so thatwhen this shaft is oscillated the table 13 will also be oscillated tomove the gear blank and the gear teeth thereon in an arcuate path, thismovement being coordinated with the reciprocation of the carriage aswill be hereinafter explained.

The oscillation of the shaft 26 from the reciprocation of the carriage22 is effected by means of flexible straps 36 and 37, these straps beingsecured at one end to the carriage as shown at 38 and 39, and the otherend of each of the straps being wrapped around a driving disk 40 securedto the shaft 26. The wrapped-around ends of the straps 36 and 37 aresecured to the disk, as shown at 41 and 42.

Slidably mounted upon the carriage 22 in ways 44 (Fig. 4) is a toolsupport 45. Suitable mechanism (not shown) is provided for moving thetool support transversely of the carriage 22 along the ways 44, thismecha nism being actuated by the hand wheel 46. As will be hereinafterexplained, the abrasive belts are carried by the tool support 45, andthe adjustment of this tool support transversely of the carriage enablesthe blets to be moved in a direction toward and from the work The toolsupport 45 is provided with an upstanding portion 47 to which is secureda drum 48, this drum being provided externally with an annulardovetailed groove or slot 49, as shown more especially in Figs. 3 and 5,and as will be explained below, the abrasive belts are directlysupported upon this drum.

Each of the belts is carried upon a frame 50, and secured to each of theframes is a rearwardly extending bracket 51 having on its inner face adovetailed lug 52 adapted to be snugly received in the dovetailed recess49 of the drum 48 so that the frames 50 may be rotatably adjusted on thedrum about the axis thereof. A set screw 53 threaded into a lug 54 uponthe bracket 51 is adapted to engage the portion 47 of the standard tohold the beltcarrying frame in the desired adjusted position.

Upon the face of the supporting frame 50 are three belt rollers orsheaves 55, 56 and 57. The shaft of the sheave 55 extends through theframe member to be driven by the motor 58 carried at the rear face ofthis member so that this motor drives the abrasive belt 59 which istrained around the rollers 55, 56 and 57.

The roller 56 is an idler roller, and its shaft may be, if desired,mounted adjustably upon the frame 50 so that it may be adjusted by theturn button 60 to maintain the abrasive belt in taut condition. Theroller 57 is also an idler roller and is of relatively small size sothat it may enter in the gap 61 between the teeth of the gear blank 14and guide the abrasive belt in engagement with a tooth of the blank intothis gap.

It may be noted that the frame 50 is set at a slight angle to the axisof the drum 48, as shown in Fig. 2, so that after the lower run of thebelt leaves the roller 57, it may run out of the space 61 so that itwill not be fouled by the teeth of the blank. It is, of course,understood that the mechanism just described for one of the abrasivebelts is duplicated for the other so that each belt has its own motor,and each can be independently adjusted with respect to the drum 48.

Each of the belts 59 is provided with a backing member 62 secured uponthe outer face of the frame member 50, this backing member lying againstthe effective area of the belt between the rollers 55 and 57 whichengages the 4. tooth of the gear so as to back up the belt at this areaand firmly support it in order that it makes positive and firmengagement with the surface of the gear tooth.

As shown in Fig, 5, if dsired, one of the belts 59 and associatedstructure may be employed to grind the teeth of a spur gear 14*. In thisinstance the procedure would be the same as that previously describedexcept that the lower run of the belt will lie below the teeth of thegear blank instead of in the gap between the teeth, as shown in Figs. 1and 3,

In the operation of the gear grinding mechanism the gear to be ground ismounted upon the table 13, as shown. The supporting frames, if two areemployed, are adjusted to the proper position on the drum 48 dependingon the helix angle of the gear to be ground. The hand wheel 46 ismanipulated to move the abrasive belts into proper position between theteeth of the gear so that the belt will engage the surface thereof. Thedevice is then placed into operation, the motors 58 driving the belts,and the carriage 22 being reciprocated by the hydraulic mechanism 23 and24. It will be apparent that upon reciprocation of the carriage the gearblank will be oscillated in an arcuate path in timed relation to themovement of the carriage so that the traveling abrasive belts 59 willcover the entire surface of one face of the tooth which is being ground.When one tooth is finished, the table 13 is indexed as previouslyexplained and a succeeding tooth may then be ground. For the indexingoperation the carriage may be moved to the left, as shown in Fig. 1, soas to remove the belt from engagement with the gear teeth and enable theblank to be rotated the distance of one tooth space.

While, as shown, the carriage is reciprocated horizontally and the gearblank supported with its axis vertically disposed, it will be understoodthat the invention is equally applicable to a device wherein the gearmay be mounted with its axis in the horizontal position and the otherparts of the device rearranged accordingly.

While I have shown and described a preferred embodiment of my invention,it will be understood that it is not to be limited to all of the detailsshown, but is capable of modification and variation within the spirit ofthe invention and within the scope of the claims.

What I claim is:

1. A gear-grinding apparatus comprising an oscillatably supported tablefor supporting a gear blank, an endless abrasive belt, a set of threesuitably supported rollers for supporting said belt and guiding it in asubstantially triangular path, means for driving one of said rollers tocause the belt to move across the face of a tooth on the blank, meansfor moving the belt in a direction generally transverse to the directionof its travel across the face of the tooth and oscillating the gearblank in synchronism with said movement, one of said rollers being ofsmall size and being positioned close to one edge of a tooth on theblank, and another of said rollers being positioned at a greaterdistance from the axis of the blank than said one roller to move thebelt sharply away from the blank.

2. A gear-grinding apparatus for grinding the teeth of a double helicalgear blank having an annular groove centrally disposed on its face, saidapparatus comprising a reciprocable carriage, an oscillatably mountedsupport for the gear blank to be ground, means for reciprocating saidcarriage and oscillating said support in synchronism, a drum mounted onthe carriage, the axis of which is substantially transverse to that ofthe support, a supporting frame mounted on said carriage carrying aplurality of rollers, an endless abrasive belt trained about saidrollers and adapted to travel across the face of a gear tooth on theblank, one of said rollers being disposed in the groove on the face ofthe blank, and means for rotatably adjusting said supporting frame aboutthe drum member.

3. A gear-grinding apparatus comprising a reciprocable 5 carriage, anoscillatably mounted support for the gear blank to be ground, means forreciprocating said carriage and oscillating said support insynchronisrn, a tool support on the carriage, a pair of supportingframes carried by said tool support, a set of three rollers on each ofsaid frames, and an endless abrasive belt trained about the rollers oneach frame for movement in a substantially triangular path, with aroller on one frame being in close proximity to a corresponding rolleron the other frame whereby the belts approach each other closely inpassing about said set of three rollers.

4. A gear-grinding apparatus as in claim 3 whereby the frames areadjustable on said tool support about an axis transverse to the axis ofthe gear blank support for the gear blank to vary the angle of the runof the belt in 15 contact with the teeth of the blank.

6 5. A gear-grinding apparatus as in claim 3 wherein the axis of one ofsaid rollers of each set is located on the side of the tooth beingground opposite that upon which the axes of the other rollers of the setare located.

References Cited in the file of this patent UNITED STATES PATENTS1,518,679 Allen Dec. 9, 1924 10 2,736,994 Whittum Mar. 6, 1956 FOREIGNPATENTS 280,998 Italy Dec. 27, 1930

